One of the outstanding problems in the field of heat shock response has been to elucidate the mechanism underlying the induction of heat shock proteins (HSPs). In this work, we initiate an analysis of the expression of heat shock groEL and dnaK genes and their promoters in S. pyogenes. The synthesis of total cellular proteins was studied upon transfer of a log-phase culture from 37 degreesC to 42 degreesC by performing 5-min pulse-labeling experiments with S-35-Met. The heat shock responses in the pathogenic Gram-positive cocci, Enterococcus faecalis and Staphylococcus aureus, were also analyzed.